Sintering in Nitrogen Atmosphere of Iron-Rich Glass-Ceramics

The sintering and the crystallization of two iron-rich glass compositions (45–75m powder fractions) were studied in air and nitrogen atmospheres. The phase formation was evaluated by differential thermal analysis, while the densification, by dilatometry; the crystalline phases were identified by X-ray diffraction and the structure observed by scanning electron microscopy. It was highlighted that, due to the absence of Fe oxidation and lower viscosity of the parent and residual glasses, the sintering in nitrogen atmospheres occurs at 100°– 200°C lower temperature. In the same time the higher amount of crystal phase, formed during sinter–crystallization in inert atmosphere, improves the mechanical properties. A value of 120 MPa for the bending strength was obtained after 1-h sintering at 960°C in N2.